Memory expansion

The document describes how to construct larger memory systems by combining multiple smaller memory chips. Specifically, an 8K x 8 memory can be made by combining two 8K x 4 memory chips, with one chip storing the upper 4 bits of the address and the other storing the lower 4 bits. A 32K x 8 memory can be constructed similarly by combining 4 8K x 4 memory chips, with two chips encoding the upper address bits and selecting the appropriate pair of chips for the lower address bits.